This invention relates to radiology, and particularly to novel apparatus for inserting an intensifying screen into an envelope containing a photographic negative without the use of a darkroom, and for extracting the negative from the package for processing.
Conventional radiographic techniques currently in use employ a cassette, where practical, containing a photosensitive negative together with an intensifying screen and means for pressing the emulsion side of the negative into contact with the screen during exposure. If it is impractical to use a cassette for the particular application involved, the intensifying screen is dispensed with and radiation dosage is increased to compensate for the correspondingly lower sensitivity of the photosensitive negative in the absence of the intensifying screen. Since the latter process requires radiation dosages which in many cases would be intolerably high, various proposals have been made for incorporating intensifying screens with negatives without the use of a rigid enclosing cassette structure. Among these, one approach that has been advanced is to incorporate the intensifier screen as a layer in an integral film unit construction with the photosensitive negative. Such a construction is shown and described, for example, in U.S. Pat. No. 3,185,841, issued on May 25, 1965 to Edwin H. Land for Photographic Product Having X-ray Intensifier Screen As An Integral Component Of The Image Receiving Sheet, and assigned to the assignee of this invention. To date, constructions of this type have not been made commercially available.
Another proposal, applicable to self-processing film units such as the Polaroid Land Type 52 4.times.5 film packets and the like, is described in U.S. Pat. No. 3,462,599, issued on Aug. 19, 1969 to Herman E. Erikson et al for Radiographic Appartus For Inserting An Intensifying Screen Into A Self-processing Photographic Film Pack, and assigned to the assignee of this invention. The latter patent describes apparatus for manipulating the self-processing film unit in a light-tight housing and thereby inserting a magnetic intensifying screen, prior to exposure of the film unit, and later removing it with the aid of a magnet. This approach requires the intensifying screen to have magnetic properties, and also makes use of the specific structural properties of the particular film unit with which it is concerned.
The object of this invention is to facilitate the association of an intensifying screen with a negative without requiring a darkroom and without placing any requirements for magnetic properties on the intensifying screen.
The above and other objects of the invention are attained by apparatus which is particularly adapted to cooperate with a photosensitive negative incorporated in an opaque envelope, such as the Polaroid transparent radiographic 8.times.10 Land Film Type TPX, for example, an 8.times.10 photosensitive unit commonly used in radiography. The Type TPX Film Packet is conventionally employed with a cassette which contains an intensifying screen, and comprises a negative having a leader extending out of an opaque envelope. This packet is placed in the cassette, and the envelope removed. After exposure, the cassette is placed in a processor, such as that shown in U.S. Pat. No. 4,200,384, issued on April 29, 1980 to Donald G. Josephson and Duncan C. Sorli for Photographic Apparatus For Coupling Together Elements Of A Self-Developing Film Unit, which is assigned to the assignee of this invention, wherein the exposed negative is associated with a receiving sheet and processed to produce a finished radiograph.
Briefly, the apparatus of the invention comprises a housing formed with a base plate in which a platen is slidably received for movement between stops formed integral with the base plate. An opaque envelope containing a negative attached to a leader extending from an open end of the envelope, such as the Type TPX film packet mentioned above, may be inserted between the platen and the base plate on the housing until one edge of an opaque encircling flap formed integral with the leader, which normally forms a light tight enclosure about the open end of the envelope, encounters a lip formed on the end of the base plate. Further movement of the envelope into the space between the platen and the base plate provides a gap between the end of the envelope and the flap on the leader into which the end of a radiographic element such as an intensifying screen, radiographic sample or the like can be inserted and moved down over and in contact with the emulsion side of the negative. The platen and envelope are then moved back together, with the platen providing needed rigidity and also forming a light seal, until the end of the envelope is again inside of and under the flap on the leader. The assemblage, now comprising the negative and intensifying screen enclosed in a light tight envelope, can then be removed and taken to the desired site for exposure.
After exposure, the radiographic packet is again placed in the apparatus of the invention, but in inverted position so that a tab attached to one end of the intensifying screen or other radiographic element now engages the lip on the base plate which originally served to stop the flap on the leader of the negative. The tab is temporarily secured to the base plate, whereupon the loaded housing can be inserted into any conventional automatic processor such as that for the Type TPX film packet. The intensifier screen, being now secured to the base plate, is retained in the envelope for reuse, while the exposed negative is drawn into the processor to form the final radiograph, either within layers on its surface, on a receiving sheet, or both.
The apparatus of the invention, and its mode of operation, will best be understood in the light of the following detailed description, together with accompanying drawings, of an illustrative embodiment of the invention .